1. Field of the Invention
The present invention generally relates to a semiconductor manufacture field, and more particularly to a vacuum pump exhaust pipe of a chemical vapor deposition apparatus and a relevant vacuum pump capable of extending the preventive maintenance cycle of the apparatus.
2. Description of Prior Art
A plasma-enhanced chemical vapor deposition apparatus is in charge of vapor depositions for forming plural thin film layers in a thin film transistor. As shown in FIG. 1, a reaction chamber of the plasma-enhanced chemical vapor deposition apparatus is denoted by 100. A vacuum pump is denoted by 200. A vacuum pump exhaust pipe is denoted by 300. A scrubber is denoted by 400. In the deposition process, the thin film is not merely formed on a surface of a substrate but also on the inner wall of the reaction chamber 100. The non-reacted gases are vented to the scrubber 400 by the vacuum pump 200 for burning process. In the entire chemical vapor deposition process, the usage percentage of the total gases is less then 10% and a large amount of non-reacted gases are vented. As the exhaust gases are vented to the outlet of the vacuum pump 200, the pressure here rises to 600 Pascal and temperature here drops to 100 degree Celsius. The density of O2 rapidly ascends. The components of the exhaust gases can be SiH4, H2, N2, NH3 and etc. The exhaust gases may react with each other or with the inner wall to generate byproduct powders. Such byproduct powders can block the vacuum pump exhaust pipe 300 at the outlet of the vacuum pump 200. Therefore, the vacuum pump exhaust pipe 300 at the outlet of the vacuum pump 200 cannot vent gases fluently and causes alarms to the main apparatus and abandoned products. The procedure of dealing the blockage in the exhaust pipe 300 at the outlet of the vacuum pump 200 is: removing the exhaust pipe 300 at the outlet of the vacuum pump 200 every two weeks. The exhaust pipe 300 is cleaned with water, dried and then re-installed. The whole preventive maintenance needs two men operations and the pipe cleaning procedure for one reaction chamber takes one hour. The manpower and the time are wasted and the uptime of the chemical vapor deposition apparatus is affected.
Consequently, there is a need to provide a vacuum pump exhaust pipe of a chemical vapor deposition apparatus and a relevant vacuum pump to solve the existing problems of prior arts.